Thanks cipa.
Unfortunately it doesn´t work for me. If I use it this way, the manager runs into a never ending loading of the resource.
There must be an other reason for this behaviour I couldn´t find out yet.
Yes, it works in the Frontend. I get the value there.
But if I use it this way, the manager runs into a never ending loading of this resource.
And secondly what I want is the id available in the manager tv field and not only after rendering for the frontend. It is the base to built a DropDown List with values from other resources. Because it depends on the resource parent I can not work with static ids.
Example:
@EVAL return $modx->resource->get('parent') .'==a';
This is the base I need to get other values depends on the parent element...